Rotary furnace, kiln, dryer, and the like



April 27, 1937. F. LLOYD ET A. 2,078,333

I ROTARY FURNACE, KILN, 'DRYER-, AND THE LIKE Filed March 21, 195e fwwawfw,

Patented Apr. 27, 1937 UNITED STATES PATENT OFFICE ROTARY FURNACE, KILN, DRYER, AND

. 'rHE LIKE Frederic Lloyd, Shemeld, and Herman Lndars, 1

London, England 6 Claims. (Cl. 202-136) This invention relates to rotary furnaces, kilns,

dryers and the like (hereinafter referred to as rotary furnaces or retorts) such as are used for example for the drying of materials or for the low temperature carbonization of substances such as coal. The passage of the charge of material undergoing treatment through a rotary furnace is nor- 4 mally regulated or is presumed to be regulated, 10 by setting the axis of the rotary furnace at a slight angle to the horizontal, the discharge end of the retort being at a lower level than the feed or charging end so that a gravitational effect is H produced which is intended to cause the material 10 undergoing treatment to travel steadily and continuou'sly from the f eed to the discharge end. As the gravitational force remains constant satisfactory passage of the material' undergoing treatrv ment through the rotary retort can only be ob- '20 tained if the friction of the material remains substantially constant throughout its passage through the retort.

It has been found that the operation of treat- 'ing for example a charge of coal by a low temperature carbonization process produces a carbonaceous mass the viscosity of which varies throughout the charge with consequent variation in its friction at various stages of its pas- Isage through the rotary retort. In the absence C3f) 'of special means to move the material along the retort there is thus a tendency for the charge to remain either incompletely carbonized or in the form of Yballed masses which may in certain 'cases block the retort. Y

It is an object of the present invention to pro- 'videa rotary furnace or retort with means where- 'by every portion of the material undergoing treatment therein can be'positively and uniformly propelled at any required speed and at any pre- (40 Ydetermined time through the rotary retort, from the charge to the discharge end thereof, irrespective of any variation in viscosity or variation in size of the material undergoing treatment. This object may be effected by providing the retort 7 45 with means for moving the material undergoing treatment positively along the retort.

The presentinvention accordingly `consists in fapparatus for the heat treatment of materials, e. g., carbonaceous materials, which comprises a Vhorizontal or substantiallyv horizontal cylindrical retort rotatable upon its axis and' provided with a central shaft carrying a series of blades set at an angle with respectto the shaft and arranged f on the same side thereof and in the same sense and means for rotating the said shaft. 'In One preferred form of the invention each of the blades takes the form ,of a segment of an ellipse, e. g.. a minor segment of an ellipse.

'I'he contour of the vanes or blades and their disposition in the furnace is such that they can be moved clear of the material undergoing treatment during any desired periods when the rotary furnace is revolving, and means may be provided for rotating the shaft carrying the blades either continuously or periodically so as to move the material towards the discharge end of the retort.

When the blades are rotated periodically they may be turned through one or more complete revolutions. It will be understood that the amount by which the material is moved forward will depend on the pitch of the blades.

The vanes or blades are so arranged upon their axis within the retort that upon rotation of the axis the whole of the internal curved surface of the retort is cleaned by the blades although the blades may not actually touch the surface of the retort.

The intermittent or continuous rotation of the blades and their characteristic segmental shape ensures that at the temperature at which e. g. carbonizing is carried out any large masses of plastic semi-coked carbonaceous material will be cut into smaller portions (which will be free to carbonize and ball by the rotation of the retort). When the retort is maintained at a temperature 'of the order of 500 C. and a material containing appreciable amounts of calling constituents iS undergoing treatment, the vanes or blades may be arranged and spaced so as to produce a prodyuct not exceeding a predetermined size.

In one convenient form of the invention the yblades are so spaced that the path of one blade ron the internal surface of the retort overlaps the path of adjacent blades. The means for 'withdrawing the carbonaceous material and the vola- .tile products from the retort are preferably 1oc'ated at that end of the retort remote from the plastic state.

Following is a description by way of example and with reference to the accompanying vdiagrammatic drawingof one form of apparatus Vfor carrying the invention into effect.

In the drawingi Figure 1 is a longitudinal section of the complete apparatus;

Figure 2 is a cross section (on a larger scale) on the line 2-2 of Figure 1;

Figure 3 is an alternative form of vane on the scale of Figure 2.

Similar parts are denoted by similar reference numerals throughout the drawing.

Referring to Figures 1 and 2, ll is a cylindrical retort supported horizontally by bearing rings l2 and i3 resting on bearing rollers I4 and I5. The retort is housed within a brickwork. housing I5 provided with lagging l'i' and is heat` ed by means of gas burners I8, the waste products of combustion passing to the flue I9. retort is rotated by means of driving gear 20 and 2l connected through a shaft 22 to the mainr driving shaft.

The retort is provided at one end with a fixed4 end plate 23 connected through a'gland 24 to rial is fed from the hopper 25 to theV retort by means of a worm feed 21, mounted on'a hollow shaft 28 driven by a pulley 29.

Through the hollow shaft 28 passes a shaft 30 extending throughout the length of the retort and provided with a driving pulley 3l. The shaft has mounted upon it a series of semi-elliptical vanes or blades a feW Vof which are shown at 32. 'I'hese blades are set at an angle to the shaft 30 and are arranged so that all the blades are in the top half of the retort together. The discharge end of the furnace terminates in a chamber 33 provided with a pipe 34 for leading away volatile products of combustion and a hopper 35 provided with a valve 36 for removing the solid products.

Figure 3 shows an alternative form of blade or vane 32 which takes the form of a minor segment of an ellipse.

In one specific form of apparatus the cylindrical retort Il is 12 feet long and 2 feet in internal diameter and is built up of welded steel plates inch thick. The shaft 30 is arranged on the axis of the retort and the vanes or blades 32 are of such a size as to approach closely to without actually touching the internal surface of the retort. The blades are spaced about 6 inches apart and are inclined to the shaft 30 at such an angle that the path of one blade over the internal surface of the retort slightly overlaps the paths of adjacent blades.

The blades are normally maintained in the upper half of the retort but may be swung over the lower half of the retort periodically in order to effect the breaking up of any material Which has agglomerated into large lumps and. in order to move the contents of the retort bodily forward towards the outlet end. The' shaft 3] may be turned once or more than once during each period of motion according to the distance it is desired to advance the charge in the retort and the vanes 32 are then returned to their position in the upper portion of the retort.

In one application of the process coal is crushed to quarter inch mesh and is mixed with 15% of finely crushed coke (coke breeze). The

retort turns at a substantially constant speed of 4 to 5 R. P. M. and the blades are normally turned through a single revolution once every five minutes.

We claimzn 1. Apparatus for the heat treatment of materials which comprises an externally heated cylindrical retort rotatable upon its axis, a central shaft passing through said retort and rotatable independently thereof, a series of blades Thev ` lindrical retort rotatable upon its axis, a central vshaft passing through said retort and rotatable rindependentlythereof, a series of blades, each in the form'of'a segment of an ellipse, secured vto said central shaft, each blade occupying only a. partof the cross section of the retort and Y forming a Working t with that portion of the a feed hopper 25 closed with a cover 26. Matewall of the retort adjacent thereto and the blades being set at an angle to the shaft and on the same side thereof and spaced apart along the shaft so that the path of one blade on the internal surface of the retort overlaps thepath of adjacent blades.

3. Apparatus for the heat treatment of materials which comprises a horizontal cylindrical retort rotatable upon its axis, a central shaft passing through said retort and rotatable independently thereof, a series of blades, each in the form of a segment of an ellipse, secured to said central shaft, each blade occupying only a part of the cross section of the retort and forming a Working t with that portion of the wall of the retort adjacent thereto and the blades being set at an angle to the shaft and on the same side thereof and spaced apart along the shaft so that the path of one blade on the internal surface of the retort overlaps the path of adjacent blades.

4. Apparatus for the heat treatment of materials which comprises an externally heated cylindrical retort rotatable upon its axis, a central shaft passing through said retort and rotatable independently thereof, a series of blades secured to said central shaft, each blade occupying only a part of the cross section of the retort and forming a working fit with that portion of the wall of the retort adjacent thereto and the blades being set at an angle to the shaft and on the same side thereof and spaced apart along the shaft `so that the path of one blade on the internal surface of the retort overlaps the path of adjacent blades, and means for turning the shaft to raise the blades to and retain them in the upper part of the retort during the rotation of the latter.

5. Apparatus for the heat treatment of materials which comprises an externally heated cylindrical retort rotatable upon its axis, a central shaft passing through said retort and rotatable independently thereof, a series of blades, each in the form of a segment of an ellipse, secured to said central shaft, each blade occupying only a part of the cross section of the retort and forming a working t with that portion of the wall of the retort adjacent thereto and the blades being set at an angle to the shaft and on the same side thereofV and spaced apart along the shaft so that the path of one blade on the internal surface of the retort overlaps the path of adjacent blades, and means for turning the central shaft to raise the blades to and retain them in the upper part of the retort during the rotation of the latter.

6. Apparatus for the heat treatment of materials which comprises a horizontal cylindrical retort rotatable upon its axis, a central shaft passing through said retort and rotatable independently thereof, a series of blades, each in the form qt" a segment of an ellipse secured to said central shaft, each blade occupying only a part of the cross section of the retort and forming a Working t with that portion of the Wall of the retort adjacent thereto and the blades being set at an angle to the shaft and on the same side thereof and spaced apart along the shaft so that the path of one blade on the interna] surface of the retort overlaps the path of adjacent blades, and means for turning the central shaft to raise the blades to and retain them in the upper part of the retort during the rotation of thelatter.

FREDERIC LLOYD.

HERMAN LINDARS. 

